Remember you may be entitled to a free or heavily discounted upgrade at:
http://www.microsystools.com/products/sitemap-generator/upgrade.php

Click here to read the sitemap generator press release at PRWeb. And please consider tweeting it if possible

Version 3 is too slow. So where can I download version 2.4 so that I can use it instead?

Are you sure you are using the exact same settings? Did you load your 2.x project into 3.x?

If so, and there is a clear difference, I would be happy to to take a look and run a few test scans if possible? Especially if website is below 10k pages or so. I have had 2 two people complain about difference between 2.3.6 and 2.3.7 (where I updated HTTP library version), but it is very hard to make proper profiling tests if scans even in release build takes hours. (The two examples I had were two 100k websites.)

Old versions here
http://www.microsystools.com/products/sitemap-generator/old-versions.php

I believe this issue was resolved over email, and it appeared to be a fluke. Later scans were normal Still, if anyone has any speed issues (or similar) or any sort! Do please report them (email, forum, whatever), but I prefer small websites that I can test and profile on. I have always catered for speed in A1SG, and it will continue to be a top priority